Filter for Fine Needle Biopsy

ABSTRACT

A biopsy needle comprises a first lumen open to a tissue penetrating distal tip of the needle for receiving a tissue sample therein and a second lumen in combination with a filter separating the first and second lumens from one another, the filter being configured to permit fluids to pass therethrough while preventing the sampled tissue from passing therethrough.

PRIORITY CLAIM

The present application claims the priority to the U.S. ProvisionalApplication Ser. No. 61/241,677, entitled “FILTER FOR FINE NEEDLEBIOPSY” filed on Sep. 11, 2009. The specification of theabove-identified application is incorporated herewith by reference

BACKGROUND

Needle biopsies are often performed to diagnose and/or stage variouspathologies. In these procedures, various size needles (i.e., 19 G, 22G, 25 G) are often employed. However, these procedures are ofteninefficient in that the sampled biopsy material is obscured by unwantedmatter (e.g., blood). Specifically, due to the increased traumaassociated with puncturing tissue, an undesirable amount of blood mayinadvertently be drawn into a needle diluting the sample and making itmore difficult to analyze the sample.

SUMMARY OF THE INVENTION

The present invention is directed to a biopsy needle comprising a firstlumen open to a tissue penetrating distal tip of the needle forreceiving a tissue sample therein and a second lumen in combination witha filter separating the first and second lumens from one another, thefilter being configured to permit fluids to pass therethrough whilepreventing the sampled tissue from passing therethrough.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a longitudinal cross-sectional view of a needle accordingto a first exemplary embodiment of the present invention; and

FIG. 2 shows a longitudinal cross-sectional view of a needle accordingto a second exemplary embodiment of the present invention.

DETAILED DESCRIPTION

The present invention, which may be further understood with reference tothe following description and the appended drawings, relates to devicesfor conducting biopsy procedures and in particular, to biopsy needles.Exemplary embodiments of the present invention provide a needle with afiltration mechanism to separate sampled target tissue from unwantedmaterials to obtain larger, undiluted samples.

An exemplary needle according to the present invention comprises anendoscopic ultrasound-guided fine-needle aspiration (“EUS-FNA”) devicefor performing biopsy procedures on a living body. The needle of thepresent invention comprises two concentrically formed chambers separatedfrom one another by a filter. The filter comprises a wall formed withmultiple openings therein sized to allow cells of unwanted tissue toflow therethrough from one chamber to another while preventing thetarget tissue from passing between the chambers. Accordingly, targettissue brought into the needle according to any known method along withany unwanted material (e.g., blood) first enters a first chamberextending longitudinally through the needle. The blood drawn into theneedle flows through the openings into the second chamber and isseparated from the target tissue which can not pass through the filter.

As shown in FIG. 1, a device 100 according to an exemplary embodiment ofthe invention includes a needle 101 housed within a protective sheath102 formed of any suitable biocompatible material as would be understoodby those skilled in the art. The sheath 102 may, for example, besubstantially rigid and includes a lumen sized and shaped to slidablyreceive the needle 101 therein. The needle 101 may be a 22 G needle asis commonly employed to obtain histological samples held within an outertube 112 received within the sheath 102. The outer tube 112 ispreferably 19 G and is separated from the needle 101 by an annular space105 extending therearound. In a preferred embodiment, the needle gaugeis within the range of 19 G-25 G, as known to those of skill in the artand, in one embodiment, may be selected such that a volume of theannular space 105 is greater than a volume of the needle 101 situatedtherein. In a preferred embodiment, the size of the annular space 105 isselected so that the acquired tissue sample is not compressedtherewithin. It is noted, however, that this is not a requirement of thepresent invention and the annular space 105 may be formed with anydimensions without deviating from the scope of the present invention.The needle 101, which may be formed as a hypotube, includes alongitudinal body 106 extending from a proximal end (not shown) to adistal end comprising an open, puncturing tip 108 extending distally ofa sealed distal end 114 of the outer tube 112. The proximal end (notshown) of the needle 101 further comprises a seal (e.g., a Touhy-Borstseal) configured to prevent the flow of air, fluids, etc. thereoutof.The seal permits a vacuum applied to the proximal end (not shown) to betransferred to the distal end of the needle 101. The seal (not shown) isalso configured to permit advancement and retraction of a stylet (notshown) received through the needle 101, as described in greater detailhereinafter. In an alternate embodiment, the needle 101 does not extendthrough the full length of the sheath 102 but rather, only along apredetermined distal portion thereof. In one preferred embodiment, theneedle 101 may extend approximately 0.305 meters from the distal end ofthe device 100. A proximal end of the needle 101 is then located aselected distance from the distal end and is operably connected to thestylet (not shown), which extends from the proximal end of the needle toa proximal end of the device 100 accessible to a user. In thisembodiment, the stylet (not shown) is provided with a latching mechanism(not shown) that prevents the distal end of the stylet (not shown) fromdisengaging a proximal end of the needle 101. The latching mechanism(not shown) may be formed as a flattened portion on the stylet (notshown) configured to engage a protrusion formed on a proximal end of theneedle 101, wherein engagement of the flattened portion with theprotrusion prevents movement of the stylet (not shown) therepast. Theprotrusion may be formed around a periphery of the proximal end of theneedle 101 so the rotation of the needle 101 does not dislodge thestylet (not shown) therefrom.

A lumen 104 extends through the needle 101 and a plurality of openings110 formed along at least a portion of the longitudinal body 106 extendthrough a wall of the needle 101 to the lumen 104 providing forcommunication between the lumens 104 and 105. The openings 110 in thisembodiment are formed along a substantially helical pattern, distributedevenly around a circumference of the longitudinal body 106. It is notedhowever, that the openings 110 may be formed in any pattern orarrangement on the needle 101 without deviating from the scope of thepresent invention. For example, in an alternate embodiment (not shown),the openings 110 may be situated along only a portion of a circumferenceof the needle 101. The diameter of each of the openings 110 is selectedto allow non-targeted materials to pass through while being too small topass target tissue. For example, where the non-targeted material isblood, each opening 110 may have a diameter of approximately 8-10 μmallowing red blood cells to flow therethrough while preventing harvestedtarget tissue from passing out. In an alternate embodiment, each of theopenings 110 may comprise a diameter in the range of 1 μm.-250 μm toconform to the requirements of a target procedure. As the diameters ofcell clusters of most tissue biopsies are greater than that of red bloodcells, the openings 110 effectively function as a red blood cell filter,permitting only liquid and red blood cells to flow therepast into thelumen 105 while maintaining the target tissue in the lumen 104. Thelumen 104 includes a stylet (not shown) therein which may be advancedinto the open distal end 108 of the needle 101 to prevent foreign matterfrom entering the needle 101 during insertion. After the needle 101 hasbeen advanced to the target site, the stylet (not shown) is withdrawnproximally into the needle 101 and the target tissue mass is penetratedto permit a target tissue sample to enter the lumen 104. Then, when theneedle 101 has been withdrawn from the body, the stylet (not shown) maybe advanced distally through the lumen 104 to eject the target tissuesample therefrom. It is further noted that the openings 110 are notrestricted to circular apertures and may comprise any size and shapeincluding, but not limited to, slits, slots, non-circular openings andany combination or pattern incorporating multiple sizes or shapes.Furthermore, the size of the openings may be chosen to accommodate thesize of the cells to be filtered therethrough, as those skilled in theart will understand.

The outer tube 112 is seated within the protective sheath 102 and thedistal end 114 thereof is sealed and tapered inward toward the needle101. An end of the tapered distal end 114 is proximal with respect tothe puncturing tip 108 of the needle 101 so that, when the distal tip108 is pushed into target tissue, the larger diameter outer tube 112 mayremain outside the target tissue mass reducing trauma thereto.Furthermore, the outer tube 112 is sized such that a frictional forcebetween the outer tube 112 and the sheath 102 is minimized and, suchthat a small annular space lies therebetween in an operativeconfiguration. It is noted that, although the present embodiment isdescribed with a rounded tapered distal end 114, the distal end of theouter tube 112 may be formed of any shape including, but not limited toa square. Furthermore, the outer tube 112 may be attached to the needle101 by any means known in the art such as adhesive bonding.

The needle 101 of the present invention may be used in a mannersubstantially similar to current procedures for the use of variousEUS-FNA devices. Specifically, the device 100 is inserted into a livingbody via any known guiding apparatus as would be understood by thoseskilled in the art (e.g., under ultrasound guidance) until a distalportion thereof is adjacent to a target tissue mass to be sampled. Asdescribed above, during insertion the stylet (not shown) is advanced toa distal-most resting position with a distal end thereof seated in theopening at the distal tip 108 to prevent non-targeted tissue fromentering the needle 101. When the target tissue portion has beenreached, the stylet (not shown) is withdrawn proximally into the lumen104 to create a space within which the tissue sample will be received.The needle 101 is then advanced distally into the target tissue drivingtarget tissue into the distal end of the lumen 104. Specifically, theneedle 101 is driven distally relative to the sheath 102 (e.g., by anyknown mechanism) to extend distally beyond the distal end 114 andpenetrate the target tissue mass. As noted earlier, the portion of theneedle 101 extending distally beyond the distal end 114 of outer tube112 may be of any length depending on the requirements of a procedure tobe performed. The sheath 102 may then be sized accordingly, so that,when retracted, the needle 101 is housed completely therein. Once thetarget tissue has been penetrated by the needle 101 and a sample of thetarget tissue has been forced into the distal end of the lumen 104,unwanted material is drawn out of the tissue sample by applying negativepressure to the lumen 105 (e.g., via a syringe coupled to a proximal endthereof). This pressure draws the blood or other unwanted materialthrough the holes 110 into the lumen 105 while the targeted sample oftissue is prevented from passing therethrough and remains in the lumen104. After the sampling process has been completed, the device 100 iswithdrawn proximally from the guiding device and removed from the body.The stylet (not shown) is once again advanced distally to eject thetarget biopsy material from the lumen 104 for analysis.

A device 200 according to an alternate embodiment of the inventionincludes a needle 201 including a substantially constant diameter outerbody 202. The outer body 202 extends to an open, tissue penetratingdistal tip 208 with a lumen 205 extending therethrough. It is noted thatalthough the embodiment of FIG. 2 is shown with particular dimensions,the dimensions of the lumen 205 and the body 202 may be modified in anyof a plurality of ways depending on the requirements of the proceduresto be performed. The device 200 further includes a stylet 216 sized andshaped for slidable insertion through the lumen 205 so that a distal endof the stylet 216 may seal the distal opening to the lumen 205. Whenretracted proximally into the needle 201, the distal end of the stylet216 is withdrawn into the lumen 205 so that sample tissue may enter thelumen 205.

As described above, during insertion of the needle 201 to a targettissue sampling site, the stylet 216 is advanced to a distalmostlocation in the lumen 205 to prevent unwanted tissue from entering theneedle 201. An outer diameter of the stylet 216 is selected to beslightly less than an inner diameter of the lumen 205 so that it may beslidably received therein. The distal end of the stylet 216 is sealed sothat, when in the distal-most position, the sealed distal end thereofprevents material from entering the lumen 205 via the opening in thedistal tip 208. A plurality of openings 210 extend through the stylet216, opening a lumen 214 extending therethrough to the lumen 205. Asdescribed in regard to the device 100 of FIG. 1, the openings 210 may bedistributed substantially evenly around a circumference thereof (e.g.,along a helical path) or in any desired pattern or distribution.Alternatively, the openings 210 may be placed in any desired positionsalong any desired path. As with the embodiment of FIG. 1, the openings210 may comprise a diameter of approximately 8-10 μm. to allow red bloodcells to pass therethrough while preventing the passage of targettissue.

When a target tissue area has been reached in the body, the stylet 216is withdrawn proximally into the cavity 206 and the needle 201 isadvanced distally (e.g., out of a guiding device) so that the puncturingtip 208 enters the target tissue. As would be understood by thoseskilled in the art, negative pressure may be transmitted through thestylet lumen 214 to the target tissue to aid in drawing target tissueinto the lumen 205. It is noted that the stylet 216 is only partiallyretracted into the lumen 205, allowing enough clearance for a biopsysample to enter therein without obstruction.

As with the device 100 of FIG. 1, the device 200 is advanced to adesired location adjacent to a target tissue mass to be sampled usingany known means with the stylet 216 in the distal-most position toprevent the introduction of non-targeted tissue into the lumen 205. Whenthe needle 204 has reached the desired position, the stylet 216 iswithdrawn proximally into the lumen 205 to free a space therewithin toreceive target tissue. The needle 204 is then inserted into the targettissue so that target tissue is forced into the lumen 205 via theopening in the distal tip 208. The user then reduces the pressure withinthe lumen 214 (e.g., via a vacuum source attached at the proximal end ofthe stylet lumen 214). This reduced pressure is communicated to thelumen 205 via the openings 210 and draws the contents of the lumen 205toward the openings 210. As the openings 210 are sized to permit thepassage of fluids such as blood therethrough while preventing passage oftargeted tissue, the fluids are drawn into the lumen 214 while thetarget tissue remains within the lumen 205. If desired, the fluids maybe withdrawn from the lumen 214 via a syringe or other mechanism aswould be understood by those skilled in the art to prevent it fromreturning to the cavity 206 where it would dilute the target tissuesample. The device 200 is withdrawn from the body and the stylet 216 maybe advanced distally to force the tissue sample out of the needle 204via the opening in the distal tip 208.

In an alternate embodiment of the device of FIG. 2, a proximal portionof the stylet 216 may be tapered. In another alternate embodiment, theopenings 210 may be replaced with a filter material placed at a distaltip of the stylet 216.

It will be apparent to those skilled in the art that variousmodifications and variations may be made to the structure andmethodology of the present invention without departing from the spiritor scope of the invention. For example, the exemplary needle of thepresent invention may be formed with any of various tip grinds.Furthermore, the filtering of fluid through the exemplary embodiment ofthe present invention need not be limited to openings in the hypotubeand may include a filtering medium (e.g., a non-woven fiber plug)situated on the needle to assist in filtering. The filtering medium canbe situated similar to the openings of FIGS. 1 and 2 or, in an alternateembodiment, may be placed over a distal opening of the needle, as thoseskilled in the art will understand. Still further, the annular space 105or cavity 206 that receives the unwanted tissue and other matter, canassume any shape known in the art and is not limited to symmetricalembodiments. Thus, the present invention covers all modifications andvariations so as they come within the scope of the appended claims andtheir equivalents.

1. A biopsy needle, comprising: a first lumen open to a tissuepenetrating distal tip of the needle for receiving a tissue sampletherein; a second lumen; and a filter separating the first and secondlumens from one another, the filter being configured to permit fluids topass therethrough while preventing the sampled tissue from passingtherethrough.
 2. The biopsy needle according to claim 1, wherein thefilter has a hole formed on a wall separating the first and secondlumens from one another.
 3. The biopsy needle according to claim 2,wherein the hole is between approximately 1 μm and 250 μm in diameter.4. The biopsy needle according to claim 1, wherein a cross-section ofthe first and second lumens is one of symmetrical and asymmetrical. 5.The biopsy needle according to claim 4, wherein the second lumensurrounds the first lumen.
 6. The biopsy needle according to claim 4,wherein the second lumen extends to a proximal port coupleable to asource of negative pressure to aspirate fluids therefrom.
 7. The biopsyneedle according to claim 1, further comprising: a stylet slidablyreceived within the first lumen, the second lumen extending through thestylet.
 8. The biopsy needle according to claim 7, wherein the filter isformed as an opening in the stylet opening the second lumen to anexterior of the stylet.
 9. The biopsy needle according to claim 7,further comprising: a piston housed within the second lumen, movement ofthe piston proximally lowering a pressure within the second lumen anddrawing fluids from the first lumen into the second lumen.
 10. Thebiopsy needle according to claim 1, wherein the filter comprises aplurality of openings sized to permit only predetermined particulatematter therethrough.
 11. The biopsy needle according to claim 10,wherein the openings are sized to permit red blood cells to passtherethrough but are sized to prevent cells of target tissue frompassing therethrough.
 12. The biopsy needle according to claim 11,wherein the openings are less than approximately 10μ in diameter. 13.The biopsy needle according to claim 12, wherein the openings aregreater than approximately 8μ in diameter.
 14. The biopsy needleaccording to claim 8, wherein the openings are distributed over thestylet in a substantially helical pattern.
 15. The biopsy needleaccording to claim 1, wherein the second lumen surrounds the first lumenwith the filter formed as a series of openings in a wall separating thefirst and second lumens from one another.
 16. The biopsy needleaccording to claim 2, wherein the filter is a membrane.
 17. The biopsyneedle according to claim 2, wherein the filter is a plug.
 18. A methodfor performing a needle biopsy, comprising: advancing a needle into atarget portion of tissue to capture a sample of the target tissue withina first lumen of the needle; and reducing a pressure within a secondlumen of the needle to draw fluids from the sampled tissue through afilter into the second lumen, the filter preventing passage into thesecond lumen of the sampled target tissue.
 19. The method of claim 18,wherein the second lumen extends within a stylet slidably receivedwithin the first lumen, the filter comprising a plurality of openings inthe stylet.